1. Field of the Invention
The present invention relates to a memory device.
2. Description of the Related Art
Semiconductor memory has become increasingly popular for use in various electronic devices. For example, non-volatile semiconductor memory is used in cellular telephones, digital cameras, personal digital assistants, mobile computing devices, non-mobile computing devices and other devices. Electrically Erasable Programmable Read Only Memory (EEPROM) and flash memory are among the most popular non-volatile semiconductor memories. Flash includes NAND and NOR technologies. During a read operation in such devices, a series of read reference voltages are applied to a set of storage elements to be read, and a determination is made as to which read reference voltage causes a storage element to become conductive. The read reference voltages are set to allow different data states of the storage elements to be distinguished.
However, techniques are needed to improve the accuracy of read operations, particularly as it is desired to put more states into the same voltage window.